Machining

Machining removes material from solid stock with cutting tools to create accurate, tight-tolerance parts across many materials and production volumes.

Overview

Machining is a subtractive manufacturing process that removes material from bar, plate, or cast stock to produce precise, functional parts. Common sub-processes include milling for prismatic and contoured features, turning for rotational parts, drilling for holes, grinding for fine finishes, EDM for hard or intricate geometries, and broaching for internal splines and keyways. Modern CNC machines handle complex geometries with consistent accuracy.

Use machining when you need tight tolerances, good surface finish, and reliable dimensional control on metals or engineering plastics. It excels at prototypes, fixtures, low-to-medium volumes, and high-value components where accuracy matters more than raw piece price. Tradeoffs include higher cost for heavy material removal, long cycle times on very large parts, and limitations on features that tools cannot reach. Thoughtful design for manufacturability—tool access, realistic tolerances, and minimizing setups—keeps pricing and lead times under control.

Common Materials

  • Aluminum 6061
  • Steel 1018
  • Stainless 304
  • Titanium 6Al-4V
  • Brass C360
  • Delrin (POM)

Tolerances

±0.001" to ±0.005"

Applications

  • Precision shafts and bushings
  • Housings and enclosures
  • Valve bodies and manifolds
  • Molds and tooling components
  • Workholding and inspection fixtures
  • Medical and aerospace brackets

When to Choose Machining

Choose machining for parts needing tight tolerances, good surface finish, and material flexibility from prototype through medium production volumes. It suits prismatic or rotational parts where tool access is reasonable. It works best when you can standardize features and tolerances instead of pushing extreme complexity into a single setup.

vs 3D printing

Pick machining when you need structural properties, surface finish, and dimensional accuracy comparable to end-use metal parts. It is better for tight tolerances, bearing fits, threaded features, and production-ready geometries, especially in common alloys like aluminum, steel, and brass.

vs Casting

Choose machining when you need better tolerances, sharper details, or when volumes do not justify tooling for castings. It is also preferred for prototypes, design iterations, and critical sealing or bearing surfaces, even when the bulk shape might later be cast and finish-machined.

vs Injection molding

Use machining for low-volume plastic parts, fast iterations, or when you need engineering plastics in geometries that do not justify mold tooling. It is ideal for fixtures, test hardware, and bridge production before committing to molded tooling.

vs Sheet metal fabrication

Select machining when you need thick sections, precise bores, complex 3D contours, or tight positional tolerances that are hard to achieve with bent sheet. It suits rigid, blocky components rather than large, thin-walled, formed structures.

vs Metal stamping

Choose machining for lower volumes, thicker materials, or parts requiring critical machined features like bores, threads, and tight-tolerance pockets. It avoids the upfront cost and design constraints of hard stamping dies while offering more geometric flexibility.

Design Considerations

  • Ensure tool access by modeling realistic cutter diameters and lengths, avoiding blind features that cannot be reached
  • Use generous internal corner radii and avoid sharp inside corners to allow standard end mills and reduce cycle time
  • Avoid thin walls, deep pockets, and extreme aspect-ratio features that cause chatter, deflection, and scrap
  • Specify tolerances no tighter than functionally required; over-tolerancing drives special tooling, inspection time, and cost
  • Standardize hole sizes, thread types, and fasteners so shops can use standard drills and taps
  • Group critical features on as few datums and setups as possible to reduce re-clamping, stack-up error, and machining time